Many catalysts containing a nickel compound are known to dimerize ethylene to butenes. For example, U.S. Pat. No. 4,528,415 discloses a process for the dimerization of ethylene using a catalyst consisting essentially of a nickel(O) complex, a phosphine compound, and an acid; U.S. Pat. No. 3,513,218 discloses an olefin dimerization process employing a catalyst comprising a nickel(II) compound, an electron donor, and an organoaluminum halide; U.S. Pat. No. 3,452,115 discloses an olefin dimerization process catalyzed by a catalyst consisting of a nickel(II) compound mixed with an alkylaluminum and a halide.
However, by using the above-referenced processes employing the catalysts disclosed, one has not always achieved high catalyst productivity, good product selectivity, or both. Additionally, some known processes require long reaction time, high temperature, or both to convert ethylene to butenes.
Because of the increasing importance of 1-butene as industrial feedstock, processes and catalysts that make even slight improvements in the availability of 1-butene over the known processes and catalysts are highly desirable.